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Biomedical subjects

W Harvey

Publications and source records attributed to W Harvey.

At least 55 records · Page 3Linked to original sources
PubMed1987

Psychological factors influencing post-operative pain and analgesic consumption.

The personality factors, post-operative pain experience and analgesic requirements after minor oral surgery under general anaesthesia of 103 patients are presented. Psychiatric morbidity, neuroticism and anxiety were related to increased pain which tended to persist longer than normal. Trait anxiety also correlated with simple analgesic consumption, and neuroticism was weakly associated with Omnopon requirements. Thus, regular analgesics prescribed for at least 3 days will anticipate the needs of such patients. Despite higher levels of anxiety and neuroticism, women did not complain of more pain or require more analgesia than men in this study. There was also no overall correlation between post-operative pain experience and analgesic requirements. Therefore analgesic tablet consumption cannot be used as a measure of pain control.

Adolescent↗
PubMed1987

The role of lipopolysaccharides in endotoxin-induced thymocyte proliferation and chondrocyte collagenase synthesis.

Crude endotoxin preparations from Haemophilus actinomycetemcomitans and Bacteroides gingivalis showed activity in the two principal bio-assays for interleukin 1--the lymphocyte activating factor assay and stimulation of chondrocyte collagenase synthesis. Lipopolysaccharides purified from the crude endotoxins had reduced activity in the chondrocyte collagenase assay. The activity of the endotoxins may be due to synergic interaction between their lipopolysaccharides and other, as yet unidentified, bacterial components.

Animals↗
PubMed1987

Interleukin-1-like activity in capsular material from Haemophilus actinomycetemcomitans.

This paper describes the activity of a bacterial surface component (capsular material, CM) in biological assays for interleukin-1 (IL-1). CM from the periodontal pathogen Haemophilus actinomycetemcomitans was tested in the following in vitro assays: mouse thymocyte proliferation (LAF assay), stimulation of collagenase and prostaglandin (PG) E2 synthesis by articular chondrocytes, and stimulation of PGE2 synthesis by fibroblasts. In all these assays, CM gave a response similar to an IL-1 preparation. This ability to mimic IL-1 suggests an important role for CM in both cell-mediated immunity and connective tissue destruction in localized juvenile periodontitis (LJP).

Animals↗
PubMed1986

Stimulation of human buccal mucosa fibroblasts in vitro by betel-nut alkaloids.

Oral submucous fibrosis (OSF) is characterized by excessive collagen production by mucosal fibroblasts and is associated with the habitual chewing of betel-nuts (Areca catechu); nut extracts stimulate fibroblast activity in vitro. The metabolism of arecoline, the major alkaloid in the nut, by human buccal mucosa fibroblasts in vitro was investigated; alkaloid metabolites extracted from culture media were analysed by gas chromatography and thin-layer chromatography. [3H]-arecoline was metabolized predominantly to [3H]-arecaidine and this was accompanied by a concentration-dependent stimulation of collagen synthesis and cell proliferation. Arecaidine was a more potent stimulator than arecoline. The rate of hydrolysis of a series of synthetic arecaidine esters (methyl, ethyl, butyl, propyl and pentyl) by fibroblasts was closely correlated with the extent of stimulation of collagen synthesis. Thus fibroblasts are responsive to the major metabolite of arecoline and hydrolysis of the ester group may be necessary for this action. Exposure of buccal mucosa fibroblasts to these alkaloids in vivo may contribute to the accumulation of collagen in OSF.

Alkaloids↗
PubMed1986

Anti-inflammatory effects of ultrasound therapy: evidence for a major placebo effect.

The value of therapeutic ultrasound (US) for reducing inflammation was tested in a double-blind controlled study in 150 patients following surgical removal of impacted lower third molars. Facial swelling, trismus, pain and serum C-reactive protein (CRP) were significantly reduced in the US-treated groups and in a placebo group ('mock' US) compared with an untreated control group. The majority of the anti-inflammatory activity was attributable to the placebo effect, and the highest intensity of US (1.5 W.cm-2) was consistently less beneficial than the lower intensities (0.1 and 0.5 W.cm-2) and the mock US.

Adolescent↗
PubMed1986

Inhibition of fibroblast proliferation and collagen synthesis by capsular material from Actinobacillus actinomycetemcomitans.

Cytotoxic effects of bacteria found in dental plaque are usually attributed to lipopolysaccharides (LPS) or ill-defined toxins. Many bacteria implicated in periodontal disease produce surface exopolymers (capsules) recently shown to stimulate bone resorption. Capsular material and LPS extracted from Actinobacillus (Haemophilus) actinomycetemcomitans were purified and examined for their effects on cultures of human gingival fibroblasts. DNA and collagen synthesis were significantly inhibited by capsular material (0.1-50 micrograms/ml). LPS caused only modest inhibition of DNA synthesis at 10 and 50 micrograms/ml, and had no effect on collagen synthesis. Release of lactate dehydrogenase from fibroblasts was not increased by LPS nor by capsular material, showing that the inhibitory effects were not due to cell death. Capsular material, but not LPS, caused a pronounced increase in cell size; a doubling of the nuclear area occurred within 72 h exposure. These results indicate that the capsule of A. actinomycetemcomitans may play an active role in the tissue destruction characterising inflammatory periodontal disease.

Actinobacillus↗
PubMed1986

In vitro inhibition of lipopolysaccharide-induced bone resorption by polymyxin B.

Lipopolysaccharide (LPS) purified from Haemophilus actinomycetemcomitans stimulates resorption and inhibits collagen synthesis in mouse calvaria bones in vitro. Addition of polymyxin B caused a dose-related inhibition of LPS-stimulated bone resorption and reversal of the inhibition of collagen synthesis. A polymyxin B to LPS ratio of 2:1 prevented bone resorption and restored collagen synthesis to control levels. The activity of polymyxin B was specific for LPS as bone resorption induced by prostaglandin E2 or parathyroid hormone was unaffected at similar concentrations. These results indicate that polymyxin B and its analogues may have potential in the treatment of periodontal disease by reducing bone loss induced by lipopolysaccharides.

Animals↗
PubMed1985

The anti-inflammatory effects of dexamethasone and therapeutic ultrasound in oral surgery.

A single blind, controlled trial was carried out to assess the anti-inflammatory effects of 10 mg dexamethasone given pre- and post-operatively and also ultrasound therapy in patients following the removal of impacted lower third molars. Facial swelling and trismus were significantly reduced in both the dexamethasone- and the ultrasound-treated groups compared with an untreated control group. This first report of the anti-inflammatory properties of ultrasound in a controlled clinical trial indicates its potential clinical use in reducing post-operative morbidity in oral surgery.

Adolescent↗
PubMed1985

HLA-typing in oral submucous fibrosis.

Oral submucous fibrosis (OSF) is a disease of the mouth and oropharynx characterised by progressive deposition of collagen leading to severe limitation of movement of the jaw in advanced cases. It is almost completely confined to inhabitants of, or migrants from India who chew 'betel nut'. The histopathological and clinical features suggest that autoimmune mechanisms may be involved. Because all chronic autoimmune diseases show disturbance in the frequencies of HLA antigens, we have HLA typed 50 OSF patients and a similar number of healthy subjects of the same ethnic origin. Raised frequencies of A10 and DR3 were observed. The results support the concept that OSF is a chronic autoimmune disease, initiated by constituents of betel nut, and occurring in genetically susceptible individuals. Genes situated in the HLA region are important determinants of genetic susceptibility in OSF.

Autoimmune Diseases↗
PubMed1984

Evidence for fibroblasts as the major source of prostacyclin and prostaglandin synthesis in dental cyst in man.

Periodontal cysts synthesize large amounts of prostaglandins and collagenase which probably cause the localized bone destruction essential for intraosseous cyst growth. Fragments of cyst wall, and fibroblasts cultured from them, synthesized prostacyclin (PGI2) in addition to prostaglandin E2 (PGE2), PGF2 alpha and collagenase in vitro. Soluble products from cultures of unstimulated and phytohaemagglutinin-stimulated blood mononuclear cells enhanced the synthesis of these prostaglandins in monolayer cultures of cyst-wall fibroblasts. It is therefore proposed that cyst capsule fibroblasts are the major source of these bone-resorbing factors, acting under the stimulus of lymphocytes and monocytes in chronically inflamed cysts. Cysts which were not infiltrated by chronic inflammatory cells (follicular cysts, a keratocyst, an ameloblastoma, and an aneurysmal bone cyst) also produced prostaglandins and collagenase, indicating that the stimulatory mechanism for the production of bone-resorbing factors in these cysts may differ from that in periodontal cysts.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

Outbreak of itching and rash. Epidemic hysteria in an elementary school.

Fifty-seven of 159 rural elementary school students had an explosive spread of pruritus and rash--a rarely described manifestation of epidemic hysteria. In a sample of 13 children (23%), each child examined had irregular, macular, erythematous lesions that were excoriated and actively changed during examination. Rash occurred only at sites readily accessible to hands. The symptoms disappeared promptly when the children left school and recurred each morning when they returned. There were no secondary family cases in sample children. School-wide attack rates were higher in girls and younger children. The outbreak resolved after two to three weeks, with identification of its nature and resumption of normal activities. Academic stresses were circumstantially linked to the outbreak.

Child↗
PubMed1983

The generation of hydroxyl and alkoxyl radicals from the interaction of ferrous bipyridyl with peroxides.

Reaction conditions by which the iron-chelate ferrous bipyridyl can be used as a Fenton reagent to generate specifically alkoxyl radical (.OR) from its corresponding alkyl hydroperoxide (ROOH) without producing hydroxyl radical (.OH) as a result of autoxidation are described. In this manner, the relative ability of common .OH-scavenging agents to react with .OH and various .OR species could be assessed. When .OH was generated from H2O2, 4-methylmercapto-2-oxobutyrate, ethanol and benzoate all were oxidized. When .OR (cumoxyl radical, t-butoxyl radical or ethoxyl radical) was generated specifically, each was found to oxidize 4-methylmercapto-2-oxobutyrate and ethanol. In contrast with .OH, however, none of the .OR radicals mediated the decarboxylation of benzoate. Cross-competition studies with the scavengers showed that, in contrast with the .OH-dependent reaction, the .OR-dependent oxidation of 4-methylmercapto-2-oxobutyrate and ethanol was not inhibited by benzoate. Rate constants for ferrous bipyridyl oxidation by ROOH and by H2O2 were found to be essentially the same, and therefore the differential oxidation of the various scavengers was not a reflection of iron-peroxide interaction, but rather an interaction between generated oxy radicals and the scavengers. In contrast with the H2O2 system, catalase did not inhibit the oxidation of 4-methylmercapto-2-oxobutyrate or ethanol by either the cumene hydroperoxide or the t-butyl hydroperoxide system, suggesting that the oxidizing species was not derived from H2O2. These results suggest that benzoate decarboxylation might serve as a more specific probe to detect the presence of .OH than either 4-methylmercapto-2-oxobutyrate or ethanol, which react readily with .OR.

Benzoates↗
PubMed1983

Collagen production by human mesothelial cells in vitro.

Serous effusions from a variety of malignant and non-malignant conditions were found to contain cells which had the morphological, histochemical and ultrastructural characteristics of mesothelial cells. In culture they were the predominant cell type and synthesised large quantities of the interstitial collagens type I and III, with the proportion of type III frequently approaching or exceeding 50 per cent. There was no evidence that they synthesised basement membrane collagen chains of type IV or type V. Since mesothelial cells are assumed to secrete the mesothelial basement membrane, the synthesis of interstitial collagens by desquamated mesothelial cells appears to reflect a change in the phenotype of collagen synthesis. We suggest that this change may be an important factor in the fibrosis of the serosal wall which frequently accompanies diseases with chronic serious effusion.

Cells, Cultured↗
PubMed1982

Reduced bone growth in rats treated with anticonvulsant drugs: a type II pseudohypoparathyroidism?

The effect of anticonvulsant drugs on bone growth and calcium metabolism was studied in Wistar strain rats. Animals were treated for 40-48 days with diphenylhydantoin (DPH) or sodium valproate (SV), or were thyroparathyroidectomized (TPTX) and maintained with thyroxine supplements. Bone growth, measured radiographically as increase in bone length, was reduced by up to 12% in the drug-treated and TPTX groups. Plasma iPTH concentrations were raised twofold- to threefold by DPH and SV. Total plasma calcium was not significantly altered in the DPH-treated rats but was elevated by SV treatment. Similarly, elevated iPTH and normal calcium values were also found in carbamazepine-treated and diazepam-treated rats in a separate experiment. Plasma alkaline phosphatase was reduced by high doses of the drugs. These results imply that anticonvulsant drugs induce end-organ resistance to PTH (a feature of pseudohypoparathyroidism), which may be responsible for some of the skeletal and dental abnormalities found in patients treated with anticonvulsants.

Animals↗